For components in organic electronics it is usually the case that the lower the voltage drop over the transport layers with p- (hole) or n- (electron) conductivity that are contained in these components, the greater the efficiency of the components. This functional relationship is valid in particular for organic light-emitting diodes (diagrammatic layer structure shown in FIG. 1) and organic solar cells (FIG. 2). Similar relationships are valid for organic field-effect transistors (FIG. 3), and in these cases in particular the efficiency of the injection of charge carriers is dependent on the level of the contact resistances. If this can be minimized, the effective mobility of the semiconductor is increased. As established in the art, in addition to the use of suitable electrically conducting organic materials, is the introduction into the layers of additional substances whose effect is to increase the intrinsic conductivity of these materials. Depending on the desired aim, a distinction is made between p- and n-dopants, enhancing in each case the p-conductivity and the n-conductivity of transport/contact layers, respectively. The number of n-dopants available for these organic electronic components is very limited, thereby restricting the design possibilities and present technical performance capacity of organic components. As well as the use of suitable dopants in OLEDs, therefore, their utilization in field-effect transistors for contact doping, particularly in the case of complementary circuits and/or bipolar components, is of great importance.
Within the literature there are a number of references which address the synthesis and the properties of phosphazenes in general. One example is the book “Superbases for organic synthesis—guanidines, amidines, phosphazenes and related organocatalysts” by Tsutomo Ishikawa (WILEY, 2009, ISBN: 978-0-470-51800-7). This topical complex is further treated, for example, in Núňez et al., J. Org. Chem. 1996, 61, 8386, which includes a description of the synthesis of hexaimidazolylcyclotriphosphazene. Not cited in these literature references, either for the phosphazenes or, in particular, for the proazaphosphatranes, are fields of use within the sector of organic electronics.
The patent literature recites the use of specifically substituted phosphazenes in organic electronics as electron conductors. Thus, for example, WO 2009/153276 A1 discloses an organic light-emitting diode comprising at least one cyclic phosphazene compound of the following formula
a light-emitting layer composed of at least one matrix material and at least one emitter material, in which the at least one matrix material comprises at least one cyclic phosphazene compound, the use of cyclic phosphazene compounds in organic light-emitting diodes, and a device selected from the group consisting of stationary screens, mobile screens, and lighting units, comprising at least one organic light-emitting diode of the invention and selected cyclic phosphazene compounds, and methods for producing them.
WO 2012 175219 A1 discloses an electronic device which comprises a compound A-B, where
in which —Ar1 is a C6-C18 arylene, which may be mono- or polycyclic and may optionally be substituted by one or more C1-C10 alkyl or C3-C10 cycloalkyl groups, —Ar2 is a C6-C18 arene skeleton, which is optionally substituted by electron-donating groups R4, —B1 and B2 independently are selected from B and Ar2, —B3 independently is selected from the same group as B, —R1, R2, and R3 independently are selected from alkyl, arylalkyl, cycloalkyl, aryl, and dialkylamino, —X is selected from 0, 1, 2, and 3, and for x>1 each Ar1 may be different, —y is a nonzero integer up to the total number of valence sites on the arene skeleton, —z is an integer from zero up to the total number of valence sites on the arene skeleton minus y, and also a corresponding compound of formula AB.
The use of specifically substituted proazaphosphatranes as n-dopants for increasing the conductivity of organic electron conductors, and not as electron conductors themselves, in contrast, is not suggested by the prior art.